webtek-devel

[Webtek-devel] Session methods

[Adrian S. <adr...@gm...>]

I thought it would be nice to be able to define my own methods on the
Session class. In other frameworks, it's possible to subclass the Session
class, add extra attributes (not necessary in the case of WebTek) and add
extra methods.

I thought it might be nice if this happened automatically. So I added code
in the Session class to check for the existance of an AppName::Session. If
it's there, it's used, otherwise the standard WebTek::Session is used.

However, i didn't get on very well. Firstly the AppName::Session is not
automatically loaded (AppName::Classname is not loaded;
AppName::Package::Classname is, which I didn't expect), and then I had a
problem where the compiler went into an infinite loop when I tried to
automatically load the class from somewhere else (I've no idea why) and so I
gave up on automatic loading and put "use AppName::Session" in the
Handler.pm. The module is loaded, but now I get the error:

You have an error in your SQL syntax; check the manual that corresponds to
your MySQL server version for the right syntax to use near '' at line 1' in
delete from session where

I.e. it tries to execute the statement "delete from session where" with no
where condition, as far as I can see.

Well, I shall continue trying tomorrow. Currently I have spent about 2 hours
on this feature. It is just to display a different text if a certain
condition is true, if certain attributes are set on the session at the same
time, i.e. all I need is one utility method actually! Maybe I can give up on
this approach if it is not possible, and e.g. put the utility method
somewhere else e.g. global function somewhere.

Do you have any advice on this matter?

Thanks, Adrian

Re: [Webtek-devel] Session methods

[max d. <pro...@gm...>]

hmm.... yes, you are right, this is really tricky. i also spent one  
hour on this problem, and now i understand, there is no clean  
solution, because:

	* the session is loaded explizit via the loader, and all Modules in  
the app-dir via WebTek::Module->load
	* the session is a model
		- a model use the init mehtod to analyze the table and set its  
properties
	* the session has the init method which inits the session (read  
request->cookie, and so on...)
		- there is a clash with the model->init method
		- so there is a hack, and this is to rename the model->init mehod to  
init_model ( i have fixed this now, but its not already checked in )
	* if you want to subclass a model, the subclass is automatically some  
thing like a 'single-table-inheritance', which additionally has some  
other magic to work
		-> so you can not simply subclass a model (as in traditionally OO  
programming)

	=> but there is a solution (because we live in perl ;) ... dirty, but  
a common perl way ;)

so in the file Model/Session.pm say:

	my $session_init = *WebTek::Session::init{'CODE'};

	*WebTek::Session::init = sub {
	   my $class = shift;

	   #... do something here
            log_info('foofoo');
            #... call the super mehtod
	   $class->$session_init();
	}

so what is this:
	* first we copy the coderef into a variable
	* then we create a anonymous subroutine with the new session-init code
		-> it has to be a anonymous subroutine to dont overwrite the  
original init method of WebTek::Session, something like:
				package WebTek::Session; sub init { ... }
			will overwrite the original init mehtod
	* this new coderef will now be called via WebTek::Session->init
		-> and within this we can call the SUPER mehtod
	* tricky isnt it ;)
		-> and this is the common way in javascript to subclass classes  
(ups... sorry instances, or still classes, who will know this in  
javascript, mr. crockford maybe?? ;)
	* simply you can use Hook::LexWrap to simplify things

hmm... i see there is a problem with webtek and OO thinking. i never  
run into such pitfalls, because i more think the webtek way (in rails  
they say, you have to think the rails way, otherwhise you get a lot of  
troubles)

the early releases was really stricktly OO, and more than that, you  
could use every webtek module in your app dir as a stand alone module,  
but this is no longer possible, because i added so much magic, which  
will simplyfy things if you know the magic, but webtek gets much more  
complex with this.. hmmm...

i think it is the time to meet you and make a refactoring of some  
parts, to dont run into such pitfalls (i remember this is not your  
first one, sorry for that...).

max.

On Sep 4, 2008, at 5:48 PM, Adrian Smith wrote:

> I thought it would be nice to be able to define my own methods on  
> the Session class. In other frameworks, it's possible to subclass  
> the Session class, add extra attributes (not necessary in the case  
> of WebTek) and add extra methods.
>
> I thought it might be nice if this happened automatically. So I  
> added code in the Session class to check for the existance of an  
> AppName::Session. If it's there, it's used, otherwise the standard  
> WebTek::Session is used.
>
> However, i didn't get on very well. Firstly the AppName::Session is  
> not automatically loaded (AppName::Classname is not loaded;  
> AppName::Package::Classname is, which I didn't expect), and then I  
> had a problem where the compiler went into an infinite loop when I  
> tried to automatically load the class from somewhere else (I've no  
> idea why) and so I gave up on automatic loading and put "use  
> AppName::Session" in the Handler.pm. The module is loaded, but now I  
> get the error:
>
> You have an error in your SQL syntax; check the manual that  
> corresponds to your MySQL server version for the right syntax to use  
> near '' at line 1' in  delete from session where
>
> I.e. it tries to execute the statement "delete from session where"  
> with no where condition, as far as I can see.
>
> Well, I shall continue trying tomorrow. Currently I have spent about  
> 2 hours on this feature. It is just to display a different text if a  
> certain condition is true, if certain attributes are set on the  
> session at the same time, i.e. all I need is one utility method  
> actually! Maybe I can give up on this approach if it is not  
> possible, and e.g. put the utility method somewhere else e.g. global  
> function somewhere.
>
> Do you have any advice on this matter?
>
> Thanks, Adrian
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